Can I change the date of my flight from my visa?

the date on my visa is "from june 23, 2011" but can I rebook my ticket after that date on my visa? I am so confused because of their note "in accordance to the new schengen agreement and regulations being implemented as of april 5, 2010 the flight booking/ticket should be submitted upon the filing of visa application and recommended that no changes be made in the travel itinerary. therefore, we inform all visa applicants that the italian embassy in manila will absolutely NO responsibility for refusal of entry by any schengen member state as a result of changes made in your travel bookings." please answer my question. thanks...